Polarizing film-integrated transparent electrically conductive film

ABSTRACT

A polarizing film-integrated transparent electrically conductive film, wherein a polysulfone film as a support layer is laminated on at least one surface of a polyvinylalcohol polarizing film which has been dyed with a water-soluble disazo compound as a free acid represented by the general formula (1) ##STR1## wherein X represents nitro group or amino group, A represents the formula (a) or (b) ##STR2## (wherein R 1  represents hydrogen atom, methoxy group, ethoxy group, methyl group or hydroxyl group, R 2  represents hydrogen atom, methyl group, methoxy group, ethoxy group, acetylamino group or ureido group, R 3  represents hydrogen atom, methoxy group or ethoxy group, and n is 0 or 1), and Y represents amino group, methylamino group, acetylamino group, N-methyl-N-acetylamino group, β-hydroxyethylamino group, or a phenylamino or benzoyl amino group in which the phenyl nucleus may be substituted by one or two of nitro group, amino group, hydroxyl group, methyl group, sulfonic acid group and carboxyl group, or a copper complex compound thereof and furthermore a transparent electrically conductive film is laminated on either one of the surfaces of the laminated film.

TECHNICAL FIELD

This invention relates to a polarizing film-integrated transparentelectrically conductive film. Particularly, this invention relates to apolarizing film-integrated transparent electrically conductive filmwherein a polysulfone film as a support layer is laminated on apolyvinylalcohol polarizing film which has been dyed with a disazocompound and furthermore a transparent electrically conductive film islaminated on the laminated film.

TECHNICAL BACKGROUND

For the purpose of simplifying a process for preparing TN-type liquidcrystal display elements and reducing its cost, there has previouslyused an organic polymer film as a support layer for a polarizing filmand to provided its surface with a transparent electrically conductivefilm so that the polarizing film and the transparent electricallyconductive film may be integrated. As a support layer for a polarizingfilm, there has hitherto been used an acetate film, for example, atriacetate cellulose film (TAC film). However, in the production of anintegral type, the TAC film has the defects that it cannot resist theconditions in sputtering or vacuum deposition for forming a transparentelectrically conductive film of high quality and the conditions inassembling liquid crystal display elements because it is inferior inheat resistance. It is not desirable either from the aspect as a supportlayer for a polarizing film that the film has low heat resistance.

Films including polyester, which have hitherto been studied astransparent electrically conductive films, are subjected to orientationby stretching in order to exhibit their high molecular characteristicsand thus have optical anisotropy. The optical anisotropy is a fataldefect for TN-type liquid crystal display elements which employ thepolarization of light.

As a polarizing element which is incorporated in a polarizing film,iodine has hitherto been used and organic dyes have recently beeninvestigated also organic dyes. However, iodine has a largesublimability and thus is insufficient in its heat resistance when it isincorporated in a polarizing film as a polarizing element. As regardsthe organic dyes, the conventional ones were considerably inferior toiodine in polarizing property.

For the purpose of achieving the simplification and cost reduction inthe production process of a TN-type liquid crystal display element bymaking an integral type of a polarizing film and a transparentelectrically conductive film which have been difficult to achieve, therehas been a requirement for the development of a polarizing elementhaving a satisfactory heat resistance and a polarizing propertycomparable to that of iodine, the development of a resin capable offorming the integral structure with a polarizing film containing thepolarizing element therein, and the like.

DISCLOSURE OF THE INVENTION

The present inventors have earnestly conducted researches for solvingthe above-mentioned problems. As a result, they have attained thepresent invention. That is to say, this invention provides a polarizingfilm-integrated transparent electrically conductive film, wherein apolysulfone film as a support layer is laminated on at least one surfaceof a polyvinylalcohol polarizing film which has been dyed with awater-soluble disazo compound as a free acid represented by the generalformula (1) ##STR3## wherein X represents nitro group or amino group, Arepresents the formula (a) or (b) ##STR4## (wherein R₁ representshydrogen atom, methoxy group, ethoxy group, methyl group or hydroxylgroup, R₂ represents hydrogen atom, methyl group, methoxy group, ethoxygroup, acetylamino group or ureido group, R₃ represents hydrogen atom,methoxy group or ethoxy group, and n is 0 or 1), Y represents aminogroup, methylamino group, acetylamino group, N-methyl-N-acetylaminogroup, a β-hydroxyethylamino group, or a phenylamino or benzoylaminogroup in which the phenyl nucleus may be substituted by one or two ofnitro group, amino group, hydroxyl group, methyl group, sulfonic acidgroup and carboxyl group, or a copper complex compound thereof, andfurthermore a transparent electrically conductive film is laminated oneither one of the surfaces of the laminated film.

BEST EMBODIMENTS FOR WORKING THE INVENTION

The disazo compound which is used as a polarizing element in thisinvention and represented by the general formula (1), is prepared by thefollowing method: A compound as a free acid represented by the generalformula (2) ##STR5## is diazotized in the usual manner and coupled witha compound represented by the general formula (3) ##STR6## wherein R₁and R₂ have the same meanings as defined above, or with a compound as afree acid represented by the general formula (4) ##STR7## wherein R₃ andn have the same meanings as defined above, to produce a monoazo compoundas a free acid represented by the general formula (5) ##STR8## wherein Ahas the same meaning as defined above, and this compound is furtherdiazotized and coupled in the usual manner with a compound as a freeacid represented by the formula (6) ##STR9## wherein Y has the samemeaning as defined above and is positioned at 6- or 7-position, toproduce a water-soluble disazo compound as a free acid represented bythe formula (7) ##STR10## wherein A and Y have the same meanings asdefined above and Y is bonded to 6- or 7-position. The compoundrepresented by the formula (7) may be further treated with coppersulfate or the like to produce a copper complex thereof. Moreover, thecompound represented by the formula (7) may be reduced with sodiumsulfate or the like to produce a compound as a free acid represented bythe formula (8) ##STR11## wherein A and Y have the same meanings asdefined above and Y is bonded to 6- or 7-position, and if necessary, itis treated with copper sulfate or the like to produce a copper complexof the compound represented by the formula (8).

The compound represented by the general formula (1) is usually preparedas a sodium salt thereof. The compound can also be prepared as a freeacid or as other salts thereof such as potassium salt, lithium salt,ammonium salt, alkylamine salt, ethanolamine salt and the like.

As the specific examples of the disazo compound represented by theformula (1), there are enumerated the following compounds: ##STR12##

Furthermore, the disazo compounds shown in the following table are alsoused. The symbol X, A and Y in the table have the same meanings as thosefor the symbols in the formula (1).

    ______________________________________                                         ##STR13##                     (1)                                                                               Formation                                                                     of copper                                  X     A           Y                complex                                    ______________________________________                                        NO.sub.2                                                                             ##STR14##  6,NH.sub.2       no                                         NO.sub.2                                                                             ##STR15##  6,NH.sub.2       yes                                        NO.sub.2                                                                             ##STR16##                                                                                 ##STR17##       no                                         NO.sub.2                                                                             ##STR18##  7,NHC.sub.2 H.sub.4 OH                                                                         no                                         NO.sub.2                                                                             ##STR19##                                                                                 ##STR20##       no                                         NO.sub.2                                                                             ##STR21##                                                                                 ##STR22##       no                                         NO.sub.2                                                                             ##STR23##                                                                                 ##STR24##       no                                         NO.sub.2                                                                             ##STR25##                                                                                 ##STR26##       no                                         NO.sub.2                                                                             ##STR27##  7,NHCH.sub.3     no                                         NO.sub.2                                                                             ##STR28##                                                                                 ##STR29##       no                                         NO.sub.2                                                                             ##STR30##                                                                                 ##STR31##       yes                                        NO.sub.2                                                                             ##STR32##  6,N(CH.sub.3).sub.2                                                                            yes                                        NO.sub.2                                                                             ##STR33##                                                                                 ##STR34##       no                                         NO.sub.2                                                                             ##STR35##  7,NH.sub.2       no                                         NO.sub.2                                                                             ##STR36##  6,NH.sub.2       no                                         NO.sub.2                                                                             ##STR37##                                                                                 ##STR38##       no                                         NO.sub.2                                                                             ##STR39##                                                                                 ##STR40##       no                                         NO.sub.2                                                                             ##STR41##                                                                                 ##STR42##       no                                         NO.sub.2                                                                             ##STR43##                                                                                 ##STR44##       no                                         NO.sub.2                                                                             ##STR45##                                                                                 ##STR46##       no                                         NO.sub.2                                                                             ##STR47##                                                                                 ##STR48##       no                                         NO.sub.2                                                                             ##STR49##  7,NH.sub.2       no                                         NO.sub.2                                                                             ##STR50##                                                                                 ##STR51##       no                                         NH.sub.2                                                                             ##STR52##  7,NH.sub.2       no                                         NH.sub.2                                                                             ##STR53##  7,NH.sub.2       no                                         NH.sub.2                                                                             ##STR54##                                                                                 ##STR55##       no                                         NH.sub.2                                                                             ##STR56##  7,NH.sub.2       no                                         NH.sub.2                                                                             ##STR57##                                                                                 ##STR58##       no                                         NH.sub.2                                                                             ##STR59##                                                                                 ##STR60##       no                                         NH.sub.2                                                                             ##STR61##                                                                                 ##STR62##       no                                         NH.sub.2                                                                             ##STR63##                                                                                 ##STR64##       no                                         NH.sub.2                                                                             ##STR65##                                                                                 ##STR66##       no                                         NH.sub.2                                                                             ##STR67##                                                                                 ##STR68##       no                                         NH.sub.2                                                                             ##STR69##  6,NHCOCH.sub.3   no                                         NH.sub.2                                                                             ##STR70##  7,NH.sub.2       no                                         NH.sub.2                                                                             ##STR71##  7,NH.sub.2       yes                                        NH.sub.2                                                                             ##STR72##  7,NH.sub.2       yes                                        NH.sub.2                                                                             ##STR73##                                                                                 ##STR74##       yes                                        NH.sub.2                                                                             ##STR75##                                                                                 ##STR76##       yes                                        NH.sub.2                                                                             ##STR77##  6,NHC.sub.2 H.sub.4 OH                                                                         yes                                        NH.sub.2                                                                             ##STR78##                                                                                 ##STR79##       yes                                        NH.sub.2                                                                             ##STR80##                                                                                 ##STR81##       yes                                        NH.sub.2                                                                             ##STR82##                                                                                 ##STR83##       yes                                        NH.sub.2                                                                             ##STR84##                                                                                 ##STR85##       yes                                        NH.sub.2                                                                             ##STR86##                                                                                 ##STR87##       yes                                         NH.sub.2                                                                            ##STR88##                                                                                 ##STR89##       yes                                        ______________________________________                                    

These compounds can be employed alone or as a mixture thereof or as amixture with other compounds (dyes).

As materials for preparing a polarizing film, there are cited, inaddition to the conventional PVA, modified polyvinyl alcohols which havebeen modified in the range of about 15 molar % or less bycopolymerization with unsaturated carboxylic acids or derivativesthereof, unsaturated sulfonic acids or derivatives thereof, an α-olefinhaving 2-30 carbon atoms, or the like, polyvinylacetals such aspolyvinylformal, polyvinylacetoacetal, polyvinylbutyral and the like,saponification products of ethylenevinyl acetate copolymers having anethylene content of 15-55 molar % (PVA type resins), and the like. Thesematerials are used in the form of a film (PVA type film) for producingpolarizing films. As a production process of dyed PVA type films, therecan be cited the method of dyeing a molded film per se, the method ofadding a dye to a solution of a PVA type resin and then forming a filmfrom the dyed solution, and the like. First of all, the general dyeingmethod and stretching method of PVA type films are now explained below.

In a dyeing bath containing a disazo compound represented by the formula(1) or a copper complex salt thereof and if necessary dyeing aids suchas an inorganic salt, a surface active agent and the like is dripped aPVA type film at a temperature of 0° C.-70° C., preferably 30°-45° C. todye it. Then, if necessary, the PVA type film is subjected to boric acidtreatment and dried. In order to afford polarizing function, the film isstretched uniaxially up to a length of 2 or more times of its originallength, particularly preferably to a length of 2.5-4 times beforedyeing, after dyeing or during dyeing. When stretching is conductedbefore dyeing or after dyeing, it may be conducted under dry conditions(generally in a range of ambient temperature to 180° C.) or wetconditions. When stretching is carried out during dyeing, the film isstretched in a dyeing bath at 0°-70° C., preferably at 30°-45° C. Themethod of forming a film after dyeing comprises first dissolving a PVAtype material (resin) into a solvent such as water, an organic solvent,a water-alcohol mixed solvent or the like and adding thereto a compoundof the formula (1) or a copper complex salt thereof to dye the solution.The dyed solution is subjected to film formation by casting method,solution coating method, extrusion method or the like to produce a dyedfilm. In order to afford polarizing function, the dyed film thusobtained is uniaxially stretched under the same wet or dry conditions asmentioned above.

The term uniaxial stretching herein means not only the stretching of afilm in a solely uniaxial direction (free width uniaxial stretching),but also the stretching including a secondary stretching to a certainextent in a direction perpendicular to the primary stretching directionin order to prevent the shrinkage in the width direction (constant widthuniaxial stretching).

As a support layer for the polarizing film, there is preferably used apolymer film which is good in transparency, optically isotropic andexcellent in heat resistance, more particularly a polymer film which hasa birefringence within 40 degrees by phase difference, a lightelasticity modulus of 2.0 mm/kg or less and a heat shrinkage factor of5% or less at 200° C. Specifically, there are used polysulfone typefilms such as polysulfone, polyether sulfone, polyarylsulfone and thelike. Particularly preferred is a polyether sulfone (hereinafterreferred to as PES) film excellent in its properties. The polysulfonetype films have transparency, mechanical strength, etching resistanceand solvent resistance required for a transparent electrode for TN-typeliquid crystal displaying elements and thus are extremely convenient. Inorder to laminate the polysulfone type films on a PVA type polarizingfilm to get a sufficient adhesive strength, it is preferable to use anadhesive which is selected from urethane resins, epoxy resins, siliconeresins and synthetic rubbers and which has a heat resistance of 2 hoursor more at a temperature of at least 120° C.

The problems to be solved by the present invention have already beenmentioned above and include the development of a polarizing elementwhich has a satisfactory heat resistance and a polarizing functioncomparable to that of iodine and the development of a resin which iscapable of forming the integral structure with a polarizing filmcontaining the polarizing element. However, for solving such problems,it is not sufficient to laminate the PVA type polarizing film and thepolysulfone type film which have been reached by this invention, merelyby use of an adhesive. Thus, the present inventors have conductedresearches as mentioned below. As a result, they have found a means forsolving the problems.

That is to say, in discussing adhesion it is first of all importantwhether the surfaces to be bonded are hydrophilic or hydrophobic. When Aand B are to be bonded, if both of the surfaces of A and B arehydrophilic or hydrophobic, a satisfactory bonding strength can berelatively easily obtained by selecting an adhesive of the same qualityas that of the two surfaces.

However, the PVA type films are essentially hydrophilic, while the PESfilms are hydrophobic. Therefore, in accomplishing the present inventionresearch has been required for increasing the bonding strength betweenthese two films which are different from each other in their properties.Moreover, the transparent electrically conductive films to be obtainedby this invention have been required as a base plate for liquid crystaldisplaying elements to maintain their qualities in various atmosphericchanges, in particular the durability at a high temperature and a highhumidity. Thus, it has been necessary to bond with a satisfactorybonding strength a hydrophilic PVA type film and a hydrophobic PES filmand to maintain the bonding strength under the conditions of hightemperature and high humidity.

The present inventors have conducted research on this point. As aresult, they have found that a laminated product which has goodproductivity and satisfactory bonding strength can be obtained by makingthe surface of a PVA type polarizing film as hydrophobic as possible andusing, as an adhesive which adheres to both of a hydrophilic surface anda hydrophobic surface with a good balance and which is low in waterabsorbency and thus excellent in humidity resistance, a UV-curing resincomprising particularly (i) a urethane acrylate obtained from adiisocyanate which will not turn to yellow, (ii) an epoxy acrylate,(iii) a (meth)acrylate, and as a light polymerization initiator (iv) oneor more of 2-methyl-1-(4-alkylthiophenyl)-2-morpholinopropan-1-ones and(v) one or more of 1-(4-alkylphenyl)-2-hydroxy-2-methylpropan-1-ones.

Next, it was necessary to solve another problem for laminating a PVAtype polarizing film and a PES film. That is, the polarizing film causedcrackings or the laminated product thereof with the PES film produced awarp.

The PVA type polarizing films are stretched axially and thus cause largeshrinking by the application of heat. Such a change in their sizes dueto heat is a problem which tends to occur also in a PVA type polarizingfilm, the both surfaces of which are coated with PES films. Thus, therehappened such problems that the polarizing film caused cracking or thelaminated product showed a warp and thus could not be used as a base fora liquid crystal displaying element.

Regarding these problems, a PES film has an advantage that its shrinkagefactor of linear expansion coefficient due to heat is scarcely differentin the axial direction (MD) and the rectangular direction (TD) and thatthe absolute value thereof is also very small, which advantage was veryimportant for achieving successfully this invention as well as theoptical properties due to its amorphous state. It has also been foundthat when the both sides of the PVA type polarizing film are coated withPES films under a satisfactory bonding strength, the behavior of thepolarizing film which exhibits anisotropy due to heat can be suppressed.Furthermore, it has been found that the bonding strength of 0.5 kg/cm ormore in the peeling test at 180° is sufficient.

The polarizing film is usually laminated on its both sides with apolysulfone type film, and if desired, a polysulfone type film may belaminated on only one side of the polarizing film and a conventionalsupport film such as a triacetate may be laminated onto the other sideof the polarizing film.

As a transparent electrically conductive substance to be laminated ontothe polysulfone type films which have been laminated on a polarizingfilm, there are selected noble metals such as gold, palladium and thelike, or metal oxides such as tin oxide, indium oxide and the like.There is generally used an oxide composite so-called as ITO (indium tinoxide), which primarily comprises indium oxide and contains 5-15% byweight of tin oxide.

As a process for laminating the transparent electrically conductivelayer, there can be used general film formation techniques such asvacuum deposition, sputtering method, ion-plating, plasma CVD, and thelike. Sputtering is particularly preferred.

When the transparent electrically conductive layer is laminated on thesurface of a polysulfone type film or a PVA type polarizing film, thebonding stability between the laminated transparent electricallyconductive layer and polysulfone type film or PVA type polarizing filmis increased by use of a UV-curable resin composition based on anepoxyacrylate, a urethane acrylate or the like, and in addition thesurface evenness of the base material (polysulfone type film or PVA typepolarizing film) is improved by the undercoating treatment.

Moreover, in order to obtain a transparent electrically conductive layerwhich is homogeneous and which has a low surface resistance and a highlight transmittance by sputtering method or the like, a base materialhaving a low gas yield is required. By the study on the laminatedproduct of a polysulfone type film and a PVA type polarizing film, ithas been found to be necessary to keep the gas yield to a level of8×10⁻⁵ m bar·1/sec·cm² or less on the measurement after one hourevacuation. As a method for lowering the gas yield to such an extent,there are cited (i) the method wherein the lamination of a polysulfonetype film and a PVA polarizing film is carried out in an atmospherewhich has been maintained at a low humidity, (ii) the method whereinboth surfaces of the base material are coated with a low moisturepermeable material, (iii) the method wherein the base material is driedin vacuum just before laminating a transparent electrically conductivelayer, and the like.

According to this invention, if desired, after a polysulfone type filmis bonded to a PVA type polarizing film, a transparent insulating layermay be provided for the purpose of preventing the transfer of steam,oxygen, ionic substances or the like before laminating a transparentelectrically conductive layer thereon. As a material for the insulatinglayer, there are used transparent metal oxides such as SiO_(x) (x=1-2),TiO₂, ZrO₂, Al₂ O₃, Ta₂ O₅, Nb₂ O₃, CeO₂, ZnO and the like. Thethickness of a layer of these metal oxides is not specifically limited,but it is preferably in the range between 100-5,000 Å. If the thicknessis less than 100 Å, a continuous film is scarcely formed, and theprevention against permeation of steam and oxygen and the effect of theprevention against the transfer of an ionic substance are insufficient.If it is more than 5,000 Å, the metal oxide layer would sometimes becracked, which is not preferable. As a method for laminating theinsulating layer, there can be used conventional film formationtechniques such as vacuum deposition, sputtering, ion-plating method,plasma CVD, and the like. Above all the RF magnetron sputtering ispreferred.

When a polysulfone type film is laminated as a support on at least oneface, preferably both faces of a polarizing film, there may be provided,on the polysulfone type film at the opposite side of a transparentelectrically conductive substance layer, a protective layer comprising ametal oxide or metal fluoride such as SiOx (x=1-2), Sb₂ O₃, CeF₃, ThO₂,CeO or the like for the purpose of protecting the polarizing element andthe polysulfone type film (support) from sunlight, particularly fromultraviolet light. In particular, SiOx (x=1-2), Sb₂ O₃ and CeF₃ areeffective for cutting the sunlight of 200-300 nm which causes yellowingof the polysulfone type film. These metal protective layers arelaminated in the same manner as the laminating process of thetransparent electrically conductive substance layer and the insulatinglayer.

Moreover, when a PES film is laminated as a support on at least one sideof a polarizing film, preferably on both sides thereof, the PES film atthe opposite side to a transparent electrically conductive substancelayer can be coated with a coating agent wherein a UV absorber has beenadded, for the purpose of protecting the PES film and the like from UVlight. In this case, if a coating agent having a lower refractive indexthan that of the PES is used, the reflection of light on the filmsurface can be decreased to improve the light transmittance of the PESfilm, and furthermore an external surface which is scarcely scratched,can be obtained by using a coating agent having a high surface hardness.As such a coating agent, there is preferably used, e.g., a silicone hardcoating agent wherein a UV absorber has been added.

As mentioned above, this invention has been achieved for obtaining apolarizing film-integrated transparent electrically conductive film byresearching a method which exhibits to maximum extent thecharacteristics of both a PVA type polarizing film which is excellent inheat resistance and which uses as a polarizing element a non-sublimatingdisazo compound having a polarizability comparable to that of an iodinetype polarizing element, and a polysulfone type film which is excellentin heat resistance and optical properties, above all PES film. Incomparison with the polarizing film-integrated transparent electricallyconductive films which have been reported, the film according to thisinvention for the first time provides a product which can be usedpractically.

By using the polarizing film-integrated transparent electricallyconductive film of the present invention, it has become possible tocarry out a continuous reel-to-reel processing with a long film, whichprocessing has hitherto been impossible for a transparent electricallyconductive film having a glass base. Thus, the time of assembling apolarizing film during the liquid crystal display element assemblingprocess can be completely saved, so that the production process of theTN-type liquid crystal display element can be simplified and the numberof the production steps can be reduced remarkably and the cost can bereduced extensively.

This invention is now explained in detail with reference to Examples.

EXAMPLE 1

A PVA film which was formed by use of a coating apparatus equipped witha doctor coater and an air-circulating type dryer, was immersed for 3min. in a solution of 40° C. which was obtained by dissolving in 10 l ofwater 10 g of a disazo compound of the formula ##STR90## and then washedwith a running water to obtain a PVA film which had been dyed blue. Thedyed film was stretched in a longitudinal direction at a ratio of 3.5with a roll type stretching machine to obtain a PVA polarizing film. Toone side of the polarizing film was bonded a PES film having a thicknessof 50 μm as a support layer, and to the other side was bonded a TAC filmcontaining a UV absorber and having a thickness of 50 μm as a protectivelayer, with a urethane adhesive, respectively. The optical properties ofthe resultant polarizing film provided with a support layer and aprotective layer were determined by a photospectrometer to show atransmittance of 45% and a polarization degree of 85% at λ_(max) 605 nm.

The PES side of the above-mentioned polarizing film was subjected toundercoating treatment, and the film was then fixed by the base holderof a high frequency magnetron sputtering apparatus, and a transparentinsulating layer of SiO₂ was formed in a thickness of 500 Å, andsubsequently a transparent electrically conductive film having athickness of 300 Å was formed in an argon plasma at 5×10⁻³ Torr with atarget comprising an indium oxide containing 7.5% by weight of tin oxideto obtain the desired polarizing film-integrated transparentelectrically conductive film.

APPLICATION EXAMPLE

A TN-type liquid crystal displaying element was prepared with thepolarizing film-integrated transparent electrically conductive filmobtained in Example 1 by the method illustrated below. On thetransparent electrically conductive surface of the film was coated apositive type photoresist by a wheeler, and after prebaking at 80° C.for 20 min. the film was exposed to UV light. Then, the film wassubjected to development and to post-baking at 80° C. for 20 min., andthe resist was peeled off after immersing and etching the film in a 6NHCl aq. solution.

On the electrode of the film which has been subjected to patterning, wasplaced a hot-melt adhesive which has been cut in the shape of a sealpattern, and on the electrode side of another film were strewed smallchips of glass fiber having a diameter of 10 μm as spacers, and the twofilms were layered and heated to a temperature of 140° C. to melt theadhesive and form a cell.

Next, by vacuum casting method, a nematic type liquid crystal was castfrom an opening which had been provided in advance, and then the openingwas sealed with an adhesive.

If the film were not integrated with a polarizing film, in thesubsequent step a polarizing plate would have to be bonded to the filmafter adjusting the axis in the polarizing direction. Since the presentfilm is of an integral type, this step can be omitted, so that theprocess can be simplified and the cost can be lowered.

EXAMPLE 2

By the use of a disazo compound of the following formula, ##STR91## aPVA polarizing film was obtained by conducting the dyeing and stretchingof the PVA film in the same manner as in Example 1. To one side of thepolarizing film was bonded a PES film having a thickness of 50 μm as asupport layer, and to the other side was laminated a TAC film having athickness of 50 μm as a protective layer, with urethane adhesive,respectively. The resultant polarizing film provided with a supportlayer and a protective layer showed a transmittance of 44% and apolarization degree of 81% at λ_(max) 572 nm.

The PES side of the above-mentioned polarizing film was subjected toundercoating treatment, and the film was then fixed by the base holderof a high frequency magnetron sputtering apparatus, and a transparentinsulating layer of SiO₂ was formed in a thickness of 500 Å, andsubsequently a transparent electrically conductive film having athickness of 300 Å was formed in an argon plasma at 5×10⁻³ Torr with atarget comprising an indium oxide containing 7.5% by weight of tin oxideto obtain the desired polarizing film-integrated transparentelectrically conductive film.

EXAMPLE 3

A PVA polarizing film was obtained with a disazo compound shown by theformula, ##STR92## in the same manner as in Example 1 by conducting thedyeing and stretching of the PVA film.

On the other hand, a PES film having a thickness of 50 μm was obtainedby extruding the PES film with a T-die extruder. This PES film waslaminated as a support layer on both surfaces of the PVA polarizing filmthrough a urethane adhesive and fixed by leaving it standing under thecondition of 40° C. for 72 hours.

One PES side of the abovementioned polarizing film was coated with anundercoat, and the film was then fixed by the base holder of a highfrequency magnetron sputtering apparatus, and a transparent insulatinglayer of SiO₂ was formed in a thickness of 500 Å, and subsequently atransparent electrically conductive film having a thickness of 300 Å waslaminated in an argon plasma at 5×10⁻³ Torr with a target comprising anindium oxide containing 7.5% by weight of tin oxide.

The other PES side was subjected to undercoating treatment, and coatedwith a film of SiO₂ as a UV-absorbing layer in a thickness of 2,000 Å bysputtering. The optical properties of the resultant polarizingfilm-integrated transparent electrically conductive film were determinedwith a photospectrometer to show a transmittance of 41% and apolarization degree of 80% at λ_(max) 606 nm.

EXAMPLE 4

In the same manner as in Example 1, a PVA polarizing film was obtained.A light-curable resin composition was prepared in the followingformulation.

    ______________________________________                                        (A)  Urethane acrylate using iso-                                                                          100    parts by                                       phoronediisocyanate as an      weight                                         isocyanate component (NIPPON                                                  GOSEI KAGAKU K. K., UV-3000B)                                            (B)  Epoxyacrylate obtained by                                                                             50     parts by                                       reacting Epicoat #1004         weight                                         (Tradename: epibis type epoxy                                                 resin manufactured by YUKA SHELL                                              EPOXY K. K.) with acrylic acid                                           (C)  2-Hydroxypropylacrylate 90     parts by                                                                      weight                                    (D)  2-Hydroxy-3-chloropropyl-                                                                             30     parts by                                       methacrylate                   weight                                    (E)  2-Methyl-1-(4-methylthiophenyl)-                                                                      3      parts by                                       2-morpholinopropan-1-one       weight                                         (Irgacure 907, manufactured by                                                Chiba-Geigy)                                                             (F)  n-Nonylphenoxyoxyethyleneacrylate                                                                     100    parts by                                                                      weight                                    (G)  1-(4-Isopropylphenyl)-2-hydroxy-                                                                      5      parts by                                       2-methylpropan-1-one           weight                                         (Darocure 1116, manufactured by                                               Merck)                                                                   ______________________________________                                    

The PVA polarizing film was inserted between 2 sheets of the PES film(70 μm thickness) the one side of which was coated with the resincomposition, and air and the excessive resin composition which werepresent between the films were removed by pressing rolls to bond tightlythe films. The laminate was immediately passed through a UV irradiatingapparatus equipped with two high-pressure mercury light of 80 W/cm at aline speed of 2 m/min. The laminate was once subjected to irradiation ofthe UV light and then heated at 120° C. for 5 min for annealing.

The results of evaluation for the peeling strength of the polarizingplate obtained are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                            Peeling Strength                                          Test Item           (kg/cm)                                                   ______________________________________                                        Normal state        >1.25 (film material                                                          was broken)                                               After heating at 140° C. for                                                               >1.23 (film material                                      2 hours             was broken)                                               After wet heating at 85° C. and                                                            1.02                                                      85% RH for 1000 hours followed                                                by treatment at 50° C. for 2                                           hours                                                                         ______________________________________                                    

EXAMPLE 5

One side of the polarizing plate obtained in Example 4 was coated with asolution prepared in the following formulation to form an undercoatlayer.

    ______________________________________                                        (A)  Urethane acrylate prepolymer                                                                       30     parts by weight                                   comprising the reaction                                                       product of isophorone                                                         diisocyanate as an isocyanate                                                 ingredient, 1,6-hexanediol as a                                               polyol ingredient and 2-hydroxy-                                              ethyl methacrylate as an acrylic                                              ingredient                                                                    (molecular weight: ca. 3,200,                                                 m.p.: 55° C.)                                                     (B)  Epoxy acrylate prepolymer                                                                          70     parts by weight                                   (molecular weight: ca. 1040,                                                  m.p.: 55° C., VR-90 manufactured                                       by SHOWA KOBUNSHI K. K.)                                                 (C)  Benzyl alcohol       300    parts by weight                              (D)  Ethylene glycol      200    parts by weight                              (E)  Methyl isobutyl ketone                                                                             150    parts by weight                              (F)  Benzoin ethyl ether  2      parts by weight                              ______________________________________                                    

The coating was conducted by using a wheeler heating at 80° C. for 10min to remove the solvent and then irradiating UV light at a distance of15 cm with a high-pressure mercury light of 80 W/cm for 30 seconds tocure the resin layer. The thickness of the coating film was 2.5 μm.

On the undercoat layer was formed a transparent electrically conductivefilm having a thickness of 300 Å in the same manner as in Example 1, andthus a polarizing film-integrated transparent electrically conductivefilm was formed.

Adhesion of the transparent electrically conductive film to thepolarizing film was evaluated in the following manner. First of all, asthe evaluation of mar resistance, several times of rubbing by use of agauze with a load was conducted, but the change of the surfaceresistance was several % or less. Next, to evaluate alkali resistance,the film was immersed in 10% NaOH for 10 min., but the change of thesurface resistance was little and no cracking was found.

EXAMPLE 6

The polarizing plate with an undercoat layer on one side obtained in thesame manner as in Examples 4 and 5 was fixed by the base holder withinthe vacuum chamber of a DC magnetron sputtering apparatus, andevacuation was continued for 1 hour. The gas yield in this case was4×10⁻⁵ m bar·1/sec·cm². Then, using a target comprising indium-tinalloy, a film of indium oxide-tin oxide composite oxide (ITO) was formedwith an argon-oxygen mixed gas plasma. The resulting ITO film had athickness of 250 Å and a surface resistance of 300 Ω/□, and it was auniform film with little unevenness.

EXAMPLE 7

The surface of the opposite side to the transparent electricallyconductive film of the polarizing film-integrated transparentelectrically conductive film obtained in Example 1 was coated with a Sitype hard coating agent (Si COAT 801, manufactured by DAIHACHI KAGAKUKOGYOSHA) to which a UV absorber had been added, in a thickness of 10μm. When the weather resistance test of the above-mentioned film wasconducted with a FADE-O-METER, neither decrease of the transmittance nordegradation of the surface was observed even after 500 hours.

Furthermore, the single plate transmittance was increased by about 1% ascompared with that of the non-coated plate. And when a liquid crystaldisplaying element was assembled with the film, there was obtaineddisplaying which is light and good in contrast.

As apparent from the above-mentioned explanations, a polarizing film, asupport layer and a transparent electrically conductive film wereintegrated to give a film for TN-type liquid crystal displaying elementwhich is excellent in polarizing function according to this invention.

INDUSTRIAL APPLICABILITY

The polarizing film-integrated transparent electrically conductive filmof the present invention in which a polarizing film, a support layer anda transparent electrically conductive film are integrated, is not onlyexcellent in polarizing capacity but also simplifies the productionprocess of a TN-type liquid crystal displaying element. Thus, it is veryuseful as a film for the TN-type liquid crystal displaying element.

We claim:
 1. A polarizing film-integrated transparent electricallyconductive film, wherein a polysulfone film as a support layer islaminated on at least one surface of a polyvinylalcohol polarizing filmwhich has been dyed with a water-soluble disazo compound as a free acidrepresented by the general formula (1) ##STR93## wherein X representsnitro group or amino group, A represents the formula (a) or (b)##STR94## wherein R₁ represents hydrogen atom, methoxy group, ethoxygroup, methyl group or hydroxyl group, R₂ represents hydrogen atom,methyl group, methoxy group, ethoxy group, acetylamino group or ureidogroup, R₃ represents hydrogen atom, methoxy group or ethoxy group, and nis 0 or 1, and Y represents amino group, methylamino group, acetylaminogroup, N-methyl-N-acetylamino group, β-hydroxyethylamino group, or aphenylamino or benzoylamino group in which the phenyl nucleus may besubstituted by one or two of nitro group, amino group, hydroxyl group,methyl group, sulfonic acid group and carboxyl group, or a coppercomplex compound thereof, and furthermore a transparent electricallyconductive film is laminated on either one of the surfaces of thelaminated film;wherein the lamination of said polyvinylalcoholpolarizing film and said polysulfone film is effected by using as anadhesive a UV-curable resin comprising (i) a urethane acrylate obtainedfrom a diisocyanate which will not turn to yellow, (ii) an epoxyacrylate, (iii) a (methy)-acrylate, and as a light polymerizationinitiator, (iv) at least one2-methyl-1-(4-akylthiophenyl)-2-morpholinopropan-1-one and (v) at leastone 1-(4-alkylphenyl)-2-hydroxy-2-methylpropan-1-one; and the laminationof said polyvinylalcohol polarizing film or said polysulfone film and atransparent electrically conductive film is effected by using as anundercoating agent a UV-curable resin composition which comprises as abase a compound selected from the group consisting of an epoxy acrylateor a urethane acrylate or a mixture thereof.
 2. A polarizingfilm-integrated transparent electrically conductive film according toclaim 1, wherein on at least one surface of said polyvinylalcoholpolarizing film is laminated a polysulfone film as a support layer andfurthermore on either one of the surfaces of said laminated film arelaminated a transparent insulating layer and a transparent electricallyconductive film.
 3. A polarizing film-integrated transparentelectrically conductive film according to claim 1, wherein on at leastone surface of said polyvinylalcohol polarizing film is laminated apolysulfone film as a support layer and furthermore on either one of thesurfaces of said laminated film are laminated a transparent insulatinglayer and a transparent electrically conductive film, while on the othersurface is laminated a transparent metal oxide layer having aUV-absorbing effect.
 4. A polarizing film integrated transparentelectrically conductive film according to claim 1, wherein the laminatedproduct of said polyvinylalcohol polarizing film and said polysulfonefilm has a gas yield of 8×10⁻⁵ m bar·1/sec·cm² or less on determinationafter one hour evacuation.
 5. A polarizing film-integrated transparentelectrically conductive film according to claim 1, wherein on at leastone surface of said polyvinylalcohol polarizing film is laminated apolysulfone film as a support layer and furthermore on either one of thesurfaces of said laminated film is laminated a transparent electricallyconductive film, while on the other surface is laminated a siliconecoating agent which contains a UV absorber and has a lower refractiveindex as compared with that of the polysulfone film and a surfacehardness higher than that of the polysulfone film.